Programmable integrated circuits (ICs) are used to implement digital logic operations according to user configurable input. One example programmable IC is a field programmable gate array (FPGA). One type of FPGA includes columns of programmable tiles. The programmable tiles comprise various types of logic blocks, which can include, for example, input/output blocks (IOBs), configurable logic blocks (CLBs), dedicated random access memory blocks (BRAM), multipliers, digital signal processing blocks (DSPs), processors, clock managers, delay lock loops (DLLs), bus or network interfaces such as Peripheral Component Interconnect Express (PCIe) and Ethernet and so forth. Each programmable tile typically includes both programmable interconnect and programmable logic. The programmable interconnect typically includes a large number of interconnect lines of varying lengths interconnected by programmable interconnect points (PIPs). The programmable logic implements the logic of a user design using programmable elements that can include, for example, function generators, registers, arithmetic logic, and so forth. Some of the columns of specialized resources, such as BRAMs, DSPs, etc., can include cascade connections along one direction, e.g., from the bottom resource to the top resource. As cascade connections are embedded inside the resource column, their performance is guaranteed by design and is more efficient than pipelines build using CLBs and programmable interconnect.
Some semiconductor devices include multiple programmable ICs mounted to an interposer. For example, rather than manufacturing one large FPGA die, multiple smaller FPGA dies are manufactured, assembled, and interconnected on the interposer. The interposer serves as a high-density printed circuit board. However, due to the limited number of connections available on the interposer, the cascade connections in the columns of specialized resources do not cross the die boundary. Thus, the maximum cascade length is shorter than would be a single large FGPA die.